People often wonder what the most important part of the solar off grid system is. The natural assumption is that it’s the solar panels themselves. But that fact is that your batteries are the muscle behind your system. Without them you’d have a great way to power your house during daylight hours and nothing else. And during daylight is probably when you use the LEAST amount of electricity!
Batteries come in every shape and size, but it’s the type that is the most important when working with solar and wind power. Most people assume that you can just hook up a car battery and away you go, but this is 100% WRONG. You need to have deep cycle batteries for a solar power system. Deep cycle batteries are what you usually find in a boat or RV.
You see, a car battery is designed for short bursts of large amounts of energy. Think about your car: it needs about 2-3 seconds of power, at a couple hundred amps, and then it’s quickly recharged by the alternator. The solar battery works differently though. It usually has lower amperage draws out of the system, but they draw for much longer. And the solar and wind power that feeds into them is often slower and steadier. So there are different batteries for different applications.
I am often asked how many batteries most people need to store energy for their home. Most off grid homes have 16 batteries, in a 4 x4 wiring arrangement, 4 in series and then 4 rows wired together. The amperage will vary depending on your consumption, but the batteries are usually around 400 amp-hours. If you remember your series and parallel wiring math, that means most off grid homes have around 1600 amp hours of capacity.
Another issue that comes up is expense; people want to know just how much they cost. Batteries are not cheap but I’ve found a neat way to cut down on those costs. This sneaky little method will save you thousands on solar batteries, car batteries and the like. It’s a way you can do it yourself, save a bunch of money and learn a neat new skill.
Batteries are also the part of the system that need the most maintenance (although it’s still not much). Twice a year I spend about 3 hours cleaning the corrosion off the connections, adding distilled water, tightening bolts, and cleaning up the battery storage area. It’s time well spent, as the better condition the batteries are in the more likely it is that they’ll last 10 years and more (which I have found to be common in well cared for batteries).
The final issue to consider with batteries is where to store them. For most climates you can store them in an out building or a shed. You would ideally have them inside a chest or cabinet inside the shed. It’s preferable not to have them in your home because they do off gas. Regardless of where they are they need good ventilation. Temperature for batteries is important, and the closer to 50 degrees you can get them the better. When batteries are cold, their performance goes down, but their life span goes up. For hot temperatures it’s just the opposite.
Hit me up with your comments and questions below.